C+S August 2023 Vol. 9 Issue 8 (web)

Trolley Route Flooding Alleviated by Stormwater Management Solutions By Nick Huston

Stormwater Management Solution The solution researched and chosen by The Walsh Group was to install a three-sided precast chamber that would allow gathering stormwater to be filtered into a pumphouse. A channel would bring water into the pumphouse from three directions, to include being funneled uphill and downhill from the chamber to the pumphouse. From the pumphouse, the stormwater would be evacuated into a chamber safely away from the trolley tracks. This action would relieve the previously flooded area and no longer affect the SEPTA line 102 from running on schedule. Several of the existing challenges remained in place throughout the construction process: on multiple occasions, a crew was in place ready to begin work following a scheduled short-term SEPTA line shutdown, only to discover with hours notice that the planned line outage had been delayed. Additionally, the crane necessary for lifting and installing the precast channel would need to be positioned next to a high-voltage power line, which resulted in the local power company being brought into the project to de-energize the line when needed. Over the course of two weekend SEPTA line 102 shutdowns, the three-sided channel installation was completed successfully in the spring of 2023. Following years and multiple construction projects together, The Walsh Group selected Oldcastle Infrastructure to provide the stormwater management solutions to the SEPTA 102 line flooding project. The companies worked closely together to ensure all challenges were met and the project was completed successfully. Products from Oldcastle Infrastructure chosen for this stormwater management project went above and beyond a typical box culvert project to include a three-sided precast channel and additional products used at multiple elevations to follow the contour of the valley. Perpendicular to the precast channel was a four-sided box that was installed in a pumphouse. The pumphouse structure was constructed on-site by Walsh as opposed to the culverts being constructed off-site and delivered to the location. A vital element of the selection of precast (vs. cast-in-place) concrete is the variables – especially the weather – are removed, as precast is typically poured in a controlled environment. One final important step during and after the stormwater solution installation was the placement and tensioning of multiple poly-strand steel cables throughout the floor of the structure to unify the channels and maintain elevation during any future acts of nature. Results As a result of the infrastructure stormwater management solution installed next to the SEPTA 102 line, the trolley is now able to run as it should, delivering riders where they need to be on time. All elements of the construction are doing their jobs, and the line no longer floods following heavy rains.

The Southeastern Pennsylvania Transportation Authority (SEPTA) trolley routes 101 and 102, sometimes called the Media-Sharon Hill line, are light rail lines serving portions of Delaware County. The Suburban Transit Division of SEPTA operates the lines, and for years they were faced with a massive challenge: a large dip in the road between stations led to constant flooding of the 102 line, which frequently resulted in a necessary closure of the trolley line, with passengers moved to buses to complete their journey. The constant flooding, caused by stormwater runoff throughout the valley area, was more than an inconvenience: it became a transportation hazard. Project contractor The Walsh Group, incorporated in 1949 and headquartered in Chicago, Illinois, offers customers services from 20 regional offices across the country, to include Pennsylvania. One of the largest and most-respected general contracting groups in the US., the Walsh Group also handles construction management and design/build work in the building, civil, and transportation sectors. With years of experience using precast solutions for stormwater management, Walsh was brought in to research the problem and find a solution. In an area fraught with constant flooding, it was clear a strong stormwater management plan would be needed to move the project forward. The stormwater would need to be pumped out of the area quickly before flooding could occur, and the solution installation would need to be timed carefully between not only the rain, but to least affect riders of the SEPTA 102 line. Thanks to H.R. 3684, the Infrastructure Investment and Jobs Act passed by Congress, the SEPTA 102 line project, along with multiple other projects in the area, fell under the necessary parameters to obtain Federal funding for a stormwater management solution. Project Challenges The challenges faced from the start were daunting: the stormwater management solution would need to be installed at night and over a weekend to minimize impact to the riding public, and the local trolley line would need to be put out of service in order for construction to occur. Coordinating all necessary integral players – from the construction team to the power company – took exceptional detailed work and no mistakes could be made.




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